County-scale distribution of polycyclic aromatic hydrocarbons in topsoil of the Yellow River Delta Region.

The Yellow River Delta (YRD) is a typical agricultural and petrochemical industrial area in China. To assess the current status of polycyclic aromatic hydrocarbons (PAHs) of soil residues, soil samples (0–15 cm) (n = 82) were collected in Bincheng District, at the geographic center of the YRD. Concentrations of 16 PAHs (∑PAHs) ranged from 181.1 to 2176.0 μg kg−1, with an average concentration of 359.8 μg kg−1, showing significant increase along a rural-urban gradient (p ≤ 0.05). The contribution of naphthalene and phenanthrene to ∑PAHs was 48.6–57.6 %, and the contribution of low molecular weight (two- and three-ring) PAHs was 56.3–66.4 % from urban to rural. The significant correlations between ∑PAHs and soil organic C and total N concentrations were observed (p ≤ 0.05), indicated soil organic C and total N can affect PAH distribution in the study area, especially for low molecular weight PAHs. Principal component and multiple linear regression analysis reveal that soil PAHs have different sources in dif...